No one at brunch is happy
The cooks -- who, mind you, are there at least an hour before anyone else in the restaurant -- aren’t happy to be there for various reasons (more on that in a sec), the servers and bartenders aren’t happy to be there because they know they’ll be working a harder shift for less pay than they would during dinner, not to mention the early call time, and none of the patrons are happy because they’re almost always hungover, hangry, and impatient. It’s a cauldron of woeful misery.
You see, the phrase “brunch is for assholes” doesn’t necessarily mean that everyone who has ever gone out for brunch is an asshole, although God knows there are plenty of those. It’s that brunch, as a meal and as a shift, turns people into assholes, both patrons and staff alike. There’s something deeply nefarious about brunch that changes people, that transforms them, people who would be perfectly lovely and pleasant during a nice dinner at a nice restaurant, but metamorphose into insufferable dickbags when it comes to that meal malignantly crammed between breakfast and lunch.